My modifications:
Floor tie down rings, having just wall track is not sufficient
Solar panels with solar charger with Lithium batteries (I need a new lithium compatible battery charger in the panel)
Wired for 120V AC with breakers+outlets, transfer switch for AC plug in
Pure sine wave inverter (for microwave), stock modified wave inverter won't run the nuke properly.
Tankless water heater
Water pumps, plumbing, sink, outdoor shower for boon-docking. We rarely stay in real campground when trailering.
Stabiler rear jacks
Window shades
Under cabinet/shelf lights
Removable base cabinets mounted to wall tracks. (summer camping)
Small fold down wall mounted tables.
Wall mounted junk trays
Queen mattress mounted/flushed to the ceiling. dropped for use
Biggest desire - Black tank, but trailer is too small for that. So we use porta-potty, Grrr
Positives:
1) As you can tell from my negatives list, there are no structural issues, no roof leaks, no flooring issues. Nothing structurally has failed. The issues all had fairly easy solutions, but took time and money and call out the need for yearly maintenance. All in all I'm very happy with the trailer. I have even hauled cars in it with no issues. The hydraulic jack is the most expensive bummer. It's even expensive to fix. Replacing with an electric jack.
2) The Vortex floor spray in liner (similar to Line-X for those who have never heard of it before - like me). I run mountain sleds with carbides. I've run sleds through the trailer now probably around 100 times. The floor is holding up well. There are no big gouges, no peeling, and the carbide marks are minimal. No apparent water damage. The ramps have the Caliber ski guides/track (very good), but you need to watch for screws popping out (only about 6 so far). I will do Vortex again - I prefer the nice flat floor for summer and cargo. The Vortex is sprayed up the wall to the tie down track (+1). Easy to pressure wash clean.
3) Towing stability - excellent. I've towed in fairly windy conditions (I-90 middle Washington, I'm from Woodinville). Moderate off-road towing for camping. The torsion axles (7K) are a quite bouncy so everything needs to be tied down, but otherwise no issues. A shock dampener would help. I have not found any frame/weld cracks.
4) Trailer height - The Logan is one of the highest off the ground trailers. I love it. Lots of clearance for snow berms and off-road angles.
5) Rust - seems to be at a minimum compared to past trailers I've owned. However, there is some under body rust, I plan to treat some next summer and probably under coat for posterity
Next trailer I will undercoat immediately. The trailer did/does have some under coating, but some areas have peeled off as it takes a beating.
6) All the other parts of the trailer are generally good. Heater, windows, doors, latches, tie downs, vents, wall hooks, cabinets/shelf, lights, switches etc. No complaints. My yearly tailer usage is roughly: 4-5 summer camping trips with RZRs, 7-10 sleds trips or more if late season snow.
Also, neither positive nor negatives, but a design consideration about the boot/glove box dryer. When on a multi-day trip I only want to run the big heater after the ride for a few hours to defrost the sleds and dry hanging jackets, but drying boots and gloves takes way longer, like overnight. Once the thermostat for the big heater reaches the set temp, it turns off, drying effectively stops. So combining boot/glove drying with the main heater is worthless, our stuff never gets fully dry. We end up using AC power boot/glove dryers in a hotel room or have to find an AC plug-in. All manufacturers seem to integrate the heater and drying this way, which doesn't work for us. The solution only works for morning "warming". The drying boxes/cabinets need to have a dedicated very small heater to run constantly and independent of the main heater all night (or just warm the items without warming the whole trailer). Our boot/glove dryer box is nothing more than a storage bin at this point. I'll be working on a new solution for drying. I'm thinking similar to the "PEET Dryer Propane Boot Dryer", but mounted in a box.